\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing, decorations.pathreplacing, decorations.shapes,}
\begin{document}
\small
\begin{tikzpicture}[>=latex,scale=1.0]
	\draw [|<->|](0.5,0)--(0.5,3)node [midway,sloped,above]{\qty{2.0}{m}};
	\draw [|-|, dashed](-1,0)--(-1,3);        
	\draw [thick](-1.4,0)--(-1,3); 
	\draw[fill=gray] (-1.4,0) circle (3pt);
	\draw[very thick] (-2, -1)--(-2, 1)node [left]{$+$}; \draw[very thick] (-.5, -1)--(-.5, 1)node [right]{$-$};
	\draw [|<->|] (-1.4,-.25)--node [below]{\qty{2.0}{cm}}(-1,-.25);
\end{tikzpicture}
\end{document}